Growth and properties of hexagonal GaN on GaAs(001) substrate by RF-molecular beam epitaxy using an AlAs nucleation layer

Hexagonal gallium nitride (h-GaN) films of about 400 nm are grown by using radio frequency (RF) plasma source assisted molecular beam epitaxy on (0 0 1)-oriented GaAs substrate. Before the growth of GaN epilayer an A1As layer of about 10 nm was grown at 700 degrees C and nitridized with the temperat ure ramping from 540 to 730 degrees C. Then low-temperature GaN or AIN was grown as the buffer layer. The epilayers were characterized by using high-r esolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and Ram an scattering. By using AIN instead of GaN as the buffer layer, the GaN epi layer quality and morphology are significantly improved. (C) 2000 Elsevier Science B.V. All rights reserved.